Various exhaust after-treatment devices have been developed to effectively limit exhaust emissions from internal combustion engines. Such after-treatment devices are typically combined into a dedicated after-treatment system as part of the engine's exhaust system.
A modern diesel engine after-treatment system generally includes a diesel particulate filter (DPF) for collecting and disposing of the sooty particulate matter or soot emitted by the diesel engine prior to the exhaust gas being discharged to the atmosphere. A typical DPF contains precious metals, such as platinum and/or palladium, which serve as catalysts to further oxidize the sooty particulate matter present in the exhaust stream.
Prior to the sooty particulate matter being trapped by the DPF, various other devices arranged in the exhaust system may come into contact with soot in the exhaust gas stream. Operation of such devices may be negatively affected as the sooty particulate matter is collected thereon.